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PubMed2005

Influence of fluoride, hydrogen peroxide and lactic acid on the corrosion resistance of commercially pure titanium.

Titanium is widely used in dental implantology and orthopaedics due to its excellent corrosion resistance and mechanical properties. However, it has been reported that Ti is sensitive to F(-), H(2)O(2) and lactic acid. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to investigate the corrosion resistance of CP-Ti disks after 9 days immersion in different test solutions, based on artificial saliva containing F(-) (0.5% and 2.5%), H(2)O(2) (0.1% and 10%) and/or lactic acid. Because activated macrophages and bacteria can also release locally some of these oxidative compounds, we investigated the role of these cells when plated onto titanium disks. The surface roughness (R(a)) was highly increased when titanium disks were immersed in artificial saliva containing F(-), H(2)O(2) and lactic acid. After 21 days of cell culture, R(a) was significantly increased on disks incubated with activated-J774.2 cells or Streptococcus mitis. AFM appeared to be more sensitive than SEM in evaluating the corrosion of the titanium. Chemical species, either environmental or those released by macrophages and bacteria, can provoke a marked attack of the titanium surface.

Animals↗
PubMedDate not supplied

Release of bovine serum albumin from preformed porous microspheres of poly(L-lactic acid).

Preformed porous microspheres of poly(L-lactic acid) (Accurel have been shown to sustain the release of highly water soluble solutes, like dextran and mannitol, for a time period of more than 4 months. The purpose of this investigation was to mechanistically characterize the release of a model protein, bovine serum albumin (BSA), from these highly porous microspheres. The microspheres were loaded with [14C]BSA in three different concentrations of 0.06, 0.26 and 0.59% w/w. The rate of release of [14C]BSA from microspheres was correlated to media ([3H]PBS) uptake. The release of BSA showed a biphasic pattern; an initial rapid release, followed by a sustained release. The initial burst of BSA was found to be inversely proportional to BSA loading and highly correlated to water penetration. The sustained release phase was independent of water penetration kinetics. Washing the microspheres did not remove either the surface bound BSA or the BSA incorporated in the microsphere matrix, indicating the tight binding of BSA to highly porous microspheres. Furthermore, addition of a surfactant induced a dramatic increase in the amount of BSA released, suggesting that the release is controlled by the surface binding of BSA to the polymer. Also, the release rate of BSA beyond the initial burst was found to be much slower than for the lower MW macromolecules like dextran at a similar level. The data from the present work suggests the BSA-polymer interaction to be a major contributing factor in explaining the overall BSA release kinetics.

Animals↗
PubMed2001

Characterization of the lactic acid bacteria in ewe's milk and cheese from northwest Argentina.

Indigenous lactic acid bacteria in ewe's milk and artisanal cheese were studied in four samples of fresh raw milk and four 1-month-old cheeses from the provinces of northwest Argentina. Mean growth counts on M17, MRS, and MSE agar media did not show significant differences (P < 0.05) in raw milk and cheeses. Isolates of lactic acid bacteria from milk were identified as Enterococcus (48%), lactococci (14%), leuconostocs (8%), and lactobacilli (30%). All lactococci were identified as Lactococcus lactis (subsp. lactis and subsp. cremoris). Lactobacilli were identified as Lactobacillus plantarum (92%) and Lactobacillus acidophilus (8%). Enterococci (59%) and lactobacilli (41%) were isolated from cheeses. L. plantarum (93%), L. acidophilus (5%), and Lactobacillus casei (2%) were most frequently isolated. L. lactis subsp. lactis biovar diacetylactis strains were considered as fast acid producers. L. lactis subsp. cremoris strains were slow acid producers. L. plantarum and L. casei strains identified from the cheeses showed slow acid production. The majority of the lactobacilli and Lactococcus lactis strains utilized citrate and produced diacetyl and acetoin in milk. Enzyme activities (API-ZYM tests) of lactococci were low, but activities of L. plantarum strains were considerably higher. The predominance of L. plantarum in artisanal cheese is probably important in the ripening of these cheeses due to their physiological and biochemical characteristics.

Animals↗
PubMed1991

Multiple quantum NMR spectroscopy methods for measuring the apparent self-diffusion coefficient of in vivo lactic acid.

Nuclear magnetic resonance spectroscopy methods are presented for measuring the apparent self-diffusion coefficient of lactic acid in vivo. These techniques incorporate diffusion-sensitive gradients into multiple quantum NMR pulse sequences that are employed for spectral editing. Both diffusion-sensitive zero quantum (ZQ) and double quantum (DQ) spectral editing techniques have been developed and the DQ method has been used to measure the apparent self-diffusion coefficient of in vivo lactic acid in H-MESO-1 human tumor xenografts subcutaneously implanted in athymic mice.

Diffusion↗
PubMed1979

Lactic acid production from molasses by mixed population of lactobacilli.

The production of lactic acid from molasses by mixed populations of (1) Lactobacillus bulgaricus AU (isolated from curd) and L. casei (supplied by NCL, Poona-8, India) and (2) L. bulgaricus, L. delbrueckii (supplied by NCL, Poona-8, India), and L. casei was studied. It has been found that association of L. bulgaricus with L. casei slightly enhances the yield of lactic acid, while the mixed population of L. bulgaricus, L. delbrueckii, and L. casei is as effective as L. bulgaricus alone.

Culture Media↗
PubMed2001

Paclitaxel loaded poly(L-lactic acid) microspheres: properties of microspheres made with low molecular weight polymers.

Microspheres were prepared from poly(L-lactic acid) polymers having molecular weights between 500 and 50k g/mol. The polymers were synthesized using two initiator molecules, L-lactic acid oligomer (PLLA-LA) or stearyl alcohol (PLLA-SA). For both PLLA-LA and PLLA-SA polymers, glass (Tg) and melting (Tm) transition temperatures and enthalpy of melting all increased as the polymer molecular weight increased. PLLA-SA showed the greatest change in Tg (-13 to 54 degrees C) as molecular weight increased from 500 to 10k x g/mol, compared to 25 to 55 degrees C for PLLA-LA polymers. Changes in Tm and enthalpy of melting with increasing molecular weight were similar for both PLLA-LA and PLLA-SA. Paclitaxel release from 30% paclitaxel loaded microspheres in the size range of 50-90 microm was affected by these changes in polymer properties as molecular weight increased. As the molecular weight increased from 2k to 50k x g/mol the amount of drug released from microspheres over 14 days decreased from 76 to 11% of the initial drug load. The release profiles were consistent with a diffusion controlled mechanism provided a two-compartment model was employed. According to this model, the total amount of 'available' drug (compartment 1) was released by diffusion in 14 days while the remainder (compartment 2) was confined within the polymeric matrix and could not diffuse out at a measurable rate. Following the in vitro release study, microsphere made from 2k-10k g/mol polymers showed significant signs of disintegration whereas 50k x g/mol polymer microspheres remained intact.

Antineoplastic Agents, Phytogenic↗
PubMedDate not supplied

[Experimental studies on the role of lactic acid in pathogenesis of neovascularization].

In order to elucidate the controversies whether lactic acid could be the factor responsible for the initiation of neovascularization, the author examined neovascular response of the vessels of the chicken chorioallantoic membrane after implantation of filter discs soaked with different concentrations of this substance. No neovascularization of the vessels of the membrane was seen after implantation of the discs. The results of the study suggest that lactic acid is not the factor which can stimulate neovascularization.

Animals↗
PubMed1997

Growth, maintenance and fermentation pattern of the salt-tolerant lactic acid bacterium Tetragenococcus halophila in anaerobic glucose limited retention cultures.

The homofermentative lactic acid bacterium Tetragenococcus halophila showed mixed acid fermentation at low growth-rates under glucose limiting conditions and in the presence of 10% NaCl. Maximum growth yields in fermentors with cell retention were not affected by pH, but maintenance requirement was at pH 5.2 four times higher than at pH 7.0. Despite the high salt-concentration of the medium, maintenance requirements were low compared to other lactic acid bacteria. The possible causes of the observed differences in maintenance requirements are discussed.

Adenosine Triphosphate↗
PubMed1999

Tissue biocompatibility of a new caprolactone-coated self-reinforced self-expandable poly-L-lactic acid bioabsorbable urethral stent.

BACKGROUND AND PURPOSE: The bioabsorption time as well as other properties of bioabsorbable polymers can be affected by the choice of the basic molecule, by the degree of its polymerization, and by the coating material used in the device. The aim of our present study was to evaluate the biocompatibility of a new caprolactone copolymer-coated, self-reinforced poly-L-lactic acid (SR-PLLA) urethral stent by means of a rabbit muscle implantation test. This new material has previously been tested for cytotoxicity using the thymidine incorporation method (DNA synthesis inhibition test), no toxicity being evidenced. MATERIALS AND METHODS: Fifteen male rabbits were used as experimental animals. Rods made from pure lactic acid, pure caprolactone copolymer, and caprolactone-coated lactic acid were placed on both sides of the dorsal muscles, eight implants per rabbit. Rods made from latex and silicone were used as positive and negative controls, respectively. The animals were sacrificed after 1 week, 1 month, or 6 months. Tissue reactions around the implants were analyzed and scored semiquantitatively. RESULTS: Acute tissue reactions attributable to operative trauma were seen in all specimens at 1 week. After 6 months, chronic inflammatory changes and foreign-body reactions were seen only in the positive controls. CONCLUSION: The new caprolactone copolymer material is highly biocompatible.

Absorption↗
PubMed1994

The potential of lactic acid bacteria for the production of safe and wholesome food.

By tradition lactic acid bacteria (LAB) are involved in the production of fermented foods. These constitute one quarter of our diet and are characterized by a safe history, certain beneficial health effects, and an extended shelf life when compared with raw materials. The various fermenting substrates are habitats for specific LAB that differ in their metabolic potential. The health effects exerted by LAB are the following: 1. Production of lactic acid and minor amounts of acetic and formic acid. These cause: a drop in pH and thereby growth inhibition of food spoiling or poisoning bacteria; killing of certain pathogens; detoxification by degradation of noxious compounds of plant origin (usually in combination with plant-derived enzymatic activities). 2. Production of antimicrobial compounds (e.g. bacteriocins, H2O2, fatty acids). 3. Probiotic effects as live organisms in food. The wholesomeness of LAB can also be extended to fields outside human nutrition, as they may act as probiotics in animal production or as plant protectives in agriculture and thus contribute to healthy raw materials for food production. Modern concepts or perspectives of the application of LAB include the following: 1. Selection of the best adapted and safely performing LAB strains. 2. Selection of strains with probiotic effects. 3. Selection of strains with health-promoting effects (e.g. production of vitamins or essential amino acids, anti-tumour activity). 4. Selection of strains with food protective activities (inhibiting spoilage or food pathogens). These strains can be added to food or used as starters in food fermentations. They may be found as wild-type organisms or can be obtained by genetic engineering.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Comparison of Clinpro Cario L-Pop estimates with CIA lactic acid estimates of the oral microflora.

Clinpro Cario L-Pop (CCLP) is a semiquantitive test claimed to determine the general potential for caries development and to monitor the individual caries risk. This test translates the capacity of the tongue microflora to produce lactic acid into a score of 1-9, indicating a low, medium or high risk for caries development. The aim of this randomized crossover, clinical trial was to evaluate the CCLP on its variation over time and its capacity to monitor the effect of three different oral hygiene procedures. The CCLP readings were compared with measurements of lactic acid in tongue biofilm and plaque samples by capillary ion electrophoresis (CIA). After four washout periods, the distribution of scores in the low-, medium-, and high-risk categories was 10%, 16%, and 74%, respectively. Out of 30 subjects, 11 scored consistently in the same category. The coefficients of variance of lactic acid concentrations were 31% for tongue samples and 25% for plaque samples. After using antimicrobial toothpaste and mouthwash, the number of high-risk scores was reduced to 33%; reduced acidogenicity was also found in tongue and plaque samples. We conclude that CCLP can be used to monitor and stimulate compliance to an antimicrobial oral hygiene protocol.

Adult↗
PubMed2000

Hydrolysis of sequenced beta-casein peptides provides new insight into peptidase activity from thermophilic lactic acid bacteria and highlights intrinsic resistance of phosphopeptides.

The peptidases of thermophilic lactic acid bacteria have a key role in the proteolysis of Swiss cheeses during warm room ripening. To compare their peptidase activities toward a dairy substrate, a tryptic/chymotryptic hydrolysate of purified beta-casein was used. Thirty-four peptides from 3 to 35 amino acids, including three phosphorylated peptides, constitute the beta-casein hydrolysate, as shown by tandem mass spectrometry. Cell extracts prepared from Lactobacillus helveticus ITG LH1, ITG LH77, and CNRZ 32, Lactobacillus delbrueckii subsp. lactis ITG LL14 and ITG LL51, L. delbrueckii subsp. bulgaricus CNRZ 397 and NCDO 1489, and Streptococcus thermophilus CNRZ 385, CIP 102303, and TA 060 were standardized in protein. The peptidase activities were assessed with the beta-casein hydrolysate as the substrate at pH 5.5 and 24 degrees C (conditions of warm room ripening) by (i) free amino acid release, (ii) reverse-phase chromatography, and (iii) identification of undigested peptides by mass spectrometry. Regardless of strain, L. helveticus was the most efficient in hydrolyzing beta-casein peptides. Interestingly, cell extracts of S. thermophilus were not able to release a significant level of free proline from the beta-casein hydrolysate, which was consistent with the identification of numerous dipeptides containing proline. With the three lactic acid bacteria tested, the phosphorylated peptides remained undigested or weakly hydrolyzed indicating their high intrinsic resistance to peptidase activities. Finally, several sets of peptides differing by a single amino acid in a C-terminal position revealed the presence of at least one carboxypeptidase in the cell extracts of these species.

Amino Acid Sequence↗
PubMed2004

[Influence of physical effort on concentration of lactic acid and acid-base equilibrium in patients with mild and moderate bronchial asthma].

PURPOSE: Estimate influences of standard physical exercise on lactic acid concentration and acid-base equilibrium in patients with mild and moderate bronchial asthma compared with healthy trained persons and do not ones. MATERIAL AND METHODS: In 47 asthmatic patients and 20 healthy persons: 1) bronchial reactivity was investigated; 2) at rest and 1, 5 and 10 min after 8 min exercise (PWC85%max, bicycle ergometer): FEV1, lactic acid concentration (LAC), pH, pO2, pCO2 and HCO3 (in capillary blood) were investigated. Among asthmatic patients: 1) 21 experienced exercise-induced asthma (EIA), 2) 20 reacted to histamine in concentration of 0.125 mg/ml/3', 3) 6 reacted to histamine in concentration of 0.25 mg/ml/3'. In healthy persons, without EIA and reaction to histamine, were: 12 who did not train, and 8 athletes. RESULTS: After exercise LAC increased in all groups (p<0.05); the increase was significantly higher in patients and persons who did not train, then athletes, and did not normalised, in opposite to athletes, however in persons who did not train was significantly lower then in asthmatics. pH and pCO2 did not change significantly in all examined persons, but HCO3 decreased significantly in patients with bronchial hyperactivity and in persons who did not train. Significant increase of pO2 appeared only in healthy persons. CONCLUSION: Physical effort caused significant greater metabolic changes in asthmatic patients then in healthy persons, especially athletes

Acid-Base Equilibrium↗
PubMed1990

Effect of lipids on the lactic acid retardation capacity of tooth enamel and cementum pellicles formed in vitro from saliva of caries-resistant and caries-susceptible human adults.

The lipid content and composition of these pellicles and the effect of lipids on their ability to retard the diffusion of lactic acid were investigated. Lipids accounted for 22.4% of the dry weight of caries-resistant enamel pellicle and 19.2% of caries-resistant cementum pellicle; the pellicle of caries-susceptible enamel contained 24.6% lipids and that of caries-susceptible cementum, 23.4%. Enamel and cementum pellicles from caries-resistant saliva had a significantly lower content of neutral lipids and phospholipids, whereas the glycolipid content was lower, although not significantly, in caries-susceptible pellicles. Pellicles from caries-resistant saliva had a considerably greater capacity to retard lactic acid diffusion than those from caries-susceptible saliva. In all cases, the retardation capacity was clearly dependent upon the lipid constituents, removal of which caused a 50-52% drop in lactic acid impedance by caries-resistant enamel and cementum pellicles, and 32-35% drop by caries-susceptible pellicles. On reacting the delipidated pellicles with their lipids, it was found that, in all cases, the highest quantitative effect on the restoration of the retardation capacity occurred when phospholipids were added. The findings suggest that the events controlling the interaction of salivary phospholipids with enamel and cementum may determine the susceptibility of the tooth surface to demineralization by acids produced by cariogenic micro-organisms.

Adult↗
PubMed1977

Serum glucose and lactic acid concentrations during prolonged and strenuous exercise in man.

Serum glucose and lactic acid levels were determined in 20 young volunteers prior to and following marches with increasing back pack loads (30 and 35 kg) and distances (6 and 12 km). The drop in serum glucose levels correlated well with the degree of effort. A significant mean drop in serum glucose level of 10.3 mg% was detected only in the group carrying 35 kg for a distance of 12 km. In this group, objective physiological parameters as well as subjective grading of the march's difficulty indicated the effort to be strenuous. Serum lactic acid level did not change significantly following any march. Serum glucose level may serve an indicator for determination of work's duration and intensity, determination of optimal distances for untrained hikers and of optimal loads to be carried for various distances.

Adolescent↗
PubMed2005

Rapid detection and counting of viable beer-spoilage lactic acid bacteria using a monoclonal chemiluminescence enzyme immunoassay and a CCD camera.

A chemiluminescence enzyme immunoassay carried out with a monoclonal antibody (MAb) and a charge-coupled device (CCD) camera was developed for rapid enumeration of viable beer-spoilage lactic acid bacteria. LA-4 MAb, which recognizes a broad spectrum of lactic acid bacteria isolated from several breweries across Spain, was produced and characterized. Test samples were filtered through polycarbonate membranes, and the membranes with retained bacteria were incubated at 31 degrees C for 2 days. They were then subjected to a two-step chemiluminescence enzyme immunoassay with MAb LA-4, and light-emitting points were detected and counted with a CCD camera. Eighteen out of 19 beer-spoilage lactic acid bacteria analysed produced luminous spots that could be enumerated. Results provided by the immunochemiluminescence assay correlated very well with those obtained by visual plate counting within a range of 3-100 CFU/100 ml. Correlation coefficients were 0.994 for four strains in sterile saline solution and 0.984 for 14 strains in artificially contaminated beer. The excellent agreement suggests that luminous spots detected within 2 days of culture are produced only by viable cells.

Animals↗
PubMed2000

High-yield fermentation of pentoses into lactic acid.

Lactobacillus species capable of fermenting glucose are generally incapable of utilizing xylose for growth or fermentation. In this study, a novel aspect of a well-known Lactobacillus strain, L. casei subsp. rhamnous (ATCC 10863), was uncovered: it can ferment xylose as efficiently as glucose. This strain is a registered organism, extremely stable on long-term operation. Fermentation by this strain is characterized by an initial lag phase lasting 24-72 h before xylose consumption takes place. The yield (grams/gram) of lactic acid from xylose is in excess of 80% with initial volumetric productivity of 0.38 g/(L.h). Acetic acid is the primary byproduct formed at the level of about 10% of the lactic acid. In addition to xylose, it can ferment all other minor sugars in hemicellulose except arabinose. Subjected to mixed sugar fermentation, this strain consumes glucose first, then mannose, followed by almost simultaneous utilization of xylose and galactose. It shows high tolerance for lactic acid as well as extraneous toxins. It can ferment the mixed sugars present in acid-treated hydrolysate of softwood, giving yields similar to that of pure sugar but at a slower rate.

Arabinose↗
PubMed1999

Involvement of manganese in conversion of phenylalanine to benzaldehyde by lactic acid bacteria.

We examined the involvement of Mn(II) in the conversion of phenylalanine to benzaldehyde in cell extracts of lactic acid bacteria. Experiments performed with Lactobacillus plantarum demonstrated that Mn(II), present at high levels in this strain, is involved in benzaldehyde formation by catalyzing the conversion of phenylpyruvic acid. Experiments performed with various lactic acid bacterial strains belonging to different genera revealed that benzaldehyde formation in a strain was related to a high Mn(II) level.

Benzaldehydes↗